#!/usr/bin/env ruby

require 'json'

require 'optparse'

options = {}

OptionParser.new do |opts|

  opts.banner = "Usage: #{$0} [OPTIONS]"

  opts.on('-l', '--left-file [FILE]', 'Left file.') do |value|
    options[:left_file] = value
  end

  opts.on('-r', '--right-file [FILE]', 'Right file.') do |value|
    options[:right_file] = value
  end

  opts.on('-e', '--left-key [JSON_FIELD_NAME]', 'Left key.') do |value|
    options[:left_key] = value
  end

  opts.on('-i', '--right-key [JSON_FIELD_NAME]', 'Right key.') do |value|
    options[:right_key] = value
  end

  opts.on('-f', '--left-prefix [STRING]', 'Left prefix to use for every field on LEFT json.') do |value|
    options[:left_prefix] = value
  end

  opts.on('-g', '--right-prefix [STRING]', 'Right prefix to use for every field on RIGHT json.') do |value|
    options[:right_prefix] = value
  end

end.parse!

required_options = [:left_file, :right_file, :left_key, :right_key, :left_prefix, :right_prefix]
required_options.each do |option|
  unless options[option]
    $stderr.puts "Can not run #{option.to_s} was not given."
    exit 1
  end
end

left = []
right = []
join = []

File.read(options[:left_file]).each_line do |line|
  left << JSON.parse(line)
end

File.read(options[:right_file]).each_line do |line|
  right << JSON.parse(line)
end

left.each do |left_item|
  right.each do |right_item|
    if left_item[options[:left_key]] == right_item[options[:right_key]]
      join_object = {}
      left_item.each do |key, value|
        join_object[options[:left_prefix] + '_' + key] = value
      end
      right_item.each do |key, value|
        join_object[options[:right_prefix] + '_' + key] = value
      end
      join << join_object
    end
  end
end

join.each do |join_item|
  puts join_item.to_json
end